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      The Smithsonian’s ‘Lights Out’ inspires visitors to save the fading night sky

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      Bright, artificial lights are drowning out the night sky’s natural glow. Now, an exhibition is highlighting some of the consequences of a fading starry night — and how people can help restore it.

      “Lights Out,” open through 2025 at the Smithsonian National Museum of Natural History in Washington, D.C., illuminates how light pollution is affecting astronomy, natural ecosystems and human cultures around the world. “We want people to understand that it’s a global problem, and it’s having broad impact,” says Jill Johnson, an exhibit developer at the museum.

      Upon entering the exhibition, the dimly lit space resets the mood for nighttime exploration. The exhibition spans a long hallway that can be entered from either end. One entrance quickly draws in visitors with a personal connection. An interactive display invites you to experience your own night sky, whether in a city, suburb or remote location. Three tactile panels feature raised elements, including dots representing light pollution and crosses indicating visible stars. The more populated a place, the more dots are smattered across the panel.

      Visitors can also listen to the artificial light and starlight in each sky through data that have been translated into sound. The multisensory experience is especially engaging for visitors who may not be able to experience the exhibition visually.

      The other entrance offers a more didactic introduction to the exhibition. A timeline presents a brief history of human-made light, from fire-lit torches to today’s LEDs, and then segues to astronomy (SN: 1/19/23). Space scientists rely on light, both visible and not, to understand celestial bodies. And their views of the universe have become increasingly obstructed by artificial light.

      “Astronomers were some of the first folks to sound the alarm on light pollution,” says Ryan Lavery, a public affairs specialist at the museum.

      Astronomers aren’t the only scientists who have noticed the repercussions. Biologists have observed light pollution’s toll on plants and animals, whether harming corals’ moonlight-triggered reproduction or bats’ ability to pollinate flowers. Here, much of the evidence on display is visual. Photographs and specimens demonstrate the variety of critters that are active at night, while a glass case of preserved birds presents the grim consequences of light pollution. All of these birds died from striking buildings in Washington, D.C., or Baltimore after being disoriented by the bright cityscapes.

      Losing dark, starry nights also affects human cultures. Another area of the exhibition presents people’s ancient and modern-day connections to the night sky through photographs, stories and cultural items. A glistening beadwork depicting the Milky Way was crafted specially for “Lights Out” by Gwich’in artist Margaret Nazon, who grew up staring at the stars in Canada’s Northwest Territories.

      Our connections under a shared sky are emphasized in the exhibition’s small central theater. It replicates a starry night over Coudersport, Pa., through speckled lighting and walls bearing illustrations of trees and hills. A short film describes the star cluster Messier 45, also known as the Pleiades, and explains the stars’ origins according to tales from three cultures — the ancient Greeks, the Ainu in Japan and the Māori in New Zealand.

      “Cultures all over the world have a deep relationship to the night sky,” says Stephen Loring, cocurator of the exhibition and an archaeologist at the museum. “If we lose the night sky, we lose an avenue to our understanding of what it is to be a human being.”

      But the exhibition isn’t all bleak. Sprinkled throughout it are success stories of how people are reducing light pollution, from France’s outdoor lighting curfews to beach communities that have altered their lighting systems to avoid drawing hatchling sea turtles away from the ocean. And visitors may be heartened to learn about simple but meaningful actions that they can take, such as aiming outdoor lights downward and using the dimmest settings.

      Overall, “Lights Out” instills a sense of hope and a desire to reconnect with the night sky. “This is an optimistic exhibition,” Loring says. “We can solve this problem.” More

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      Venus has almost 50 times as many volcanoes as previously thought

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      The hellscape of Venus is riddled with even more volcanoes than scientists thought.

      Using radar images taken by NASA’s Magellan spacecraft in the 1990s, researchers cataloged about 85,000 volcanoes strewn across the Venusian surface. That’s nearly 50 times as many volcanoes as past surveys counted. Planetary scientists Rebecca Hahn and Paul Byrne of Washington University in St. Louis debuted the map in the April JGR Planets.

      Such a thorough inventory of volcanism on Venus could offer clues about the planet’s interior, such as hot spots of magma production, Byrne says. And with the recent discovery that Venus is volcanically active, the map could also help pinpoint places to look for new eruptions (SN: 3/15/23).

      Almost all the volcanoes that Hahn and Byrne found are less than 5 kilometers wide. About 700 are 5 to 100 kilometers across, and about 100 are wider than 100 kilometers. The team also found many tight clusters of small volcanoes called volcanic fields.

      “We have a better handle of how many volcanoes are on Venus than are on Earth,” where most volcanoes are probably hidden beneath the oceans, Byrne says. But he doesn’t think the Magellan data tell the whole story of Venus’ volcanism. That spacecraft could see features as small as about 1 kilometer in diameter. Earth has “lots and lots of volcanoes that are far smaller than a kilometer across,” Byrne says. “That’s probably the case with Venus, too.”

      We may soon find out. NASA’s VERITAS spacecraft and the European Space Agency’s EnVision mission are slated to turn their much sharper eyes on Venus’ infernal surface within the next decade or so (SN: 6/2/21).    More

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      A stream of cold gas is unexpectedly feeding the far-off Anthill Galaxy

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      A long, cold stream of gas is feeding a very distant galaxy like a vast bendy straw. The finding suggests a new way for galaxies to grow in the early universe, researchers report in the March 31 Science.

      Computer simulations predicted that streams of gas should connect galaxies to the cosmic web (SN: 3/6/23). But astronomers expected that gas to be warm, making it unsuitable for star-forming fuel and galaxy growth.

      So astronomer Bjorn Emonts and his colleagues were surprised to see a stream of cold, star-forming gas leading into the Anthill Galaxy, a massive galaxy whose light takes 12 billion years to reach Earth.

      The team spotted the stream while mapping cold gas in the galaxy’s neighborhood using the Atacama Large Millimeter/submillimeter Array, or ALMA, in Chile. Emonts was particularly interested in radio wavelengths of light that carbon atoms emit when the temperature is between about -260° and -160° Celsius.

      “People didn’t think that these streams could get so cold,” says Emonts, of the National Radio Astronomy Observatory in Charlottesville, Va.

      But there, in the data, a frigid stream stretched at least 325,000 light-years away from the galaxy. The stream carries the mass of 70 billion suns and deposits the equivalent of about 450 suns in cold gas onto the galaxy every year, the team calculated. That’s enough to double the galaxy’s mass within a billion years.

      Emonts thinks that no one had seen such a stream before because his team used ALMA in an unusual configuration, with its telescopes arranged as close together as possible. That gave the observatory lower resolution, but a wider field of view.

      “People don’t normally do that,” Emonts says. “We basically defocused ALMA to the worst possible extent.”

      If other galaxies are fed by similar structures, it could mean that early galaxies grew mostly by drinking directly from the cosmic streams, rather than by the leading hypothesis — violent galaxy mergers (SN: 6/28/19). More

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      Planets without stars might have moons suitable for life

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      NOORDWIJK, THE NETHERLANDS — Life might arise in the darkest of places: the moon of a planet wandering the galaxy without a star.

      The gravitational tug-of-war between a moon and its planet can keep certain satellites toasty enough for liquid water to exist there — a condition widely considered crucial for life. Now computer simulations suggest that, given the right orbit and atmosphere, some moons orbiting rogue planets can stay warm for over a billion years, astrophysicist Giulia Roccetti reported March 23 at the PLANET-ESLAB 2023 Symposium. She and her colleagues also report their findings March 20 in the International Journal of Astrobiology.

      “There might be many places in the universe where habitable conditions can be present,” says Roccetti, of the European Southern Observatory in Garching, Germany. But life presumably also needs long-term stability. “What we are looking for is places where these habitable conditions can be sustained for hundreds of millions, or billions, of years.”

      Habitability and stability don’t necessarily need to come from a nearby sun. Astronomers have spotted about 100 starless planets, some possibly formed from gas and dust clouds the way stars form, others probably ejected from their home solar systems (SN: 7/24/17). Computer simulations suggest that there may be as many of these free-floating planets as there are stars in the galaxy.

      Such orphaned planets might also have moons — and in 2021, researchers calculated that these moons need not be cold and barren places.

      Unless a moon’s orbit is a perfect circle, the gravitational pull of its planet continually deforms it. Resulting friction inside the moon generates heat. In our own solar system, this process plays out on moons such as Saturn’s Enceladus and Jupiter’s Europa (SN: 11/6/17; SN: 8/6/20). A sufficiently thick, heat-trapping atmosphere, likely one dominated by carbon dioxide, might then keep the surface warm enough for water to remain liquid. That water could come from chemical reactions with the carbon dioxide and hydrogen in the atmosphere, initiated by the impact of high-speed charged particles from space.

      But such a moon won’t stay warm forever. The same gravitational forces that heat it up also mold its orbit into a circle. Gradually, the ebb and flow of gravity felt by the moon deforms it less and less, and the supply of frictional heat dwindles.

      In the new study, Roccetti and her colleagues ran 8,000 computer simulations of a sunlike star with three Jupiter-sized planets. These simulations showed that planets that are ejected from their solar system will often sail off into space with their moons in tow.

      The team then ran simulations of those moons, assumed to be the size of Earth, whizzing around their planets along the orbit they ended up with during the ejection. The goal was to see if gravitational heating occurred and if it lasted long enough for life to potentially originate there. Earth may have become habitable within a few hundred million years, although the earliest evidence of living organisms here date to about 1 billion years after the planet formed (SN: 1/26/18).

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      Because an atmosphere is crucial to heat retention, the team did their calculations with three alternatives. For moons with an atmosphere the same pressure as Earth’s, the period of potential habitability lasted at most about 50 million years, the team found. But it can last nearly 300 million years if the atmospheric pressure is 10 times that of Earth, and for about 1.6 billion years at pressures 10 times greater still. That amount of pressure may sound extreme, but it’s close to conditions on the similarly sized Venus.

      Warmth and water might not be enough to let living organisms appear, though. Moons of free-floating planets “will not be the most favorable places for life to arise,” says astrophysicist Alex Teachey, of the Academia Sinica Institute of Astronomy & Astrophysics in Taipei, Taiwan.

      “I think stars, due to their incredible power output and their longevity, are going to be far better sources of energy for life,” says Teachey, who studies the moons of exoplanets. “A big open question … is whether you can even start life in a place like Europa or Enceladus, even if the conditions are right to sustain life, because you don’t have, for example, solar radiation that can help along the process of mutation for evolution.”

      But Roccetti — although not an astrobiologist herself — thinks moons of orphan planets have a few  important advantages. They will have some, but not too much, water, which many astrobiologists think is a better starting point for life than, say, an ocean world. And not having a star nearby means there are no solar flares, which in many cases will destroy the atmosphere of an otherwise promising planet.

      “There are many environments in our universe which are very different from what we have here on Earth,” she says, “and it is important to investigate all of them.” More

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      Baby Jupiter glowed so brightly it might have desiccated its moon

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      THE WOODLANDS, TEXAS — A young, ultrabright Jupiter may have desiccated its now hellish moon Io. The planet’s bygone brilliance could have also vaporized water on Europa and Ganymede, planetary scientist Carver Bierson reported March 17 at the Lunar and Planetary Science Conference. If true, the findings could help researchers narrow the search for icy exomoons by eliminating unlikely orbits.

      Jupiter is among the brightest specks in our night sky. But past studies have indicated that during its infancy, Jupiter was far more luminous. “About 10 thousand times more luminous,” said Bierson, of Arizona State University in Tempe.

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      That radiance would have been inescapable for the giant planet’s moons, the largest of which are volcanic Io, ice-shelled Europa, aurora-cowled Ganymede and crater-laden Callisto (SN: 12/22/22, SN: 4/19/22, SN: 3/12/15). The constitutions of these four bodies obey a trend: The more distant the moon from Jupiter, the more ice-rich its body is.

      Bierson and his colleagues hypothesized this pattern was a legacy of Jupiter’s past radiance. The team used computers to simulate how an infant Jupiter may have warmed its moons, starting with Io, the closest of the four. During its first few million years, Io’s surface temperature may have exceeded 26° Celsius under Jupiter’s glow, Bierson said. “That’s Earthlike temperatures.”

      Any ice present on Io at that time, roughly 4.5 billion years ago, probably would have melted into an ocean. That water would have progressively evaporated into an atmosphere. And that atmosphere, hardly restrained by the moon’s weak gravity, would have readily escaped into space. In just a few million years, Io could have lost as much water as Ganymede may hold today, which may be more than 25 times the amount in Earth’s oceans.

      A coruscant Jupiter probably didn’t remove significant amounts of ice from Europa or Ganymede, the researchers found, unless Jupiter was brighter than simulated or the moons orbited closer than they do today.

      The findings suggest that icy exomoons probably don’t orbit all that close to massive planets. More

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      A neutron star collision may have emitted a fast radio burst

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      A neutron star pileup may have emitted two different kinds of cosmic signals: ripples in spacetime known as gravitational waves and a brief blip of energy called a fast radio burst.

      One of the three detectors that make up the gravitational wave observatory LIGO picked up a signal from a cosmic collision on April 25, 2019. About 2.5 hours later, a fast radio burst detector picked up a signal from the same region of sky, researchers report March 27 in Nature Astronomy.

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      If strengthened by further observations, the finding could bolster the theory that mysterious fast radio bursts have multiple origins — and neutron star mergers are one of them.

      “We’re 99.5 percent sure” the two signals came from the same event, says astrophysicist Alexandra Moroianu, who spotted the merger and its aftermath while at the University of Western Australia in Perth. “We want to be 99.999 percent sure.”

      Unfortunately, LIGO’s two other detectors didn’t catch the signal, so it’s impossible to precisely triangulate its location. “Even though it’s not a concrete, bang-on observation for something that’s been theorized for a decade, it’s the first evidence we’ve got,” Moroianu says. “If this is true … it’s going to be a big boom in fast radio burst science.”

      Mysterious radio bursts

      Astronomers have spotted more than 600 fast radio bursts, or FRBs, since 2007. Despite their frequency, the causes remain a mystery. One leading candidate is a highly magnetized neutron star called a magnetar, which could be left behind after a massive star explodes (SN: 6/4/20). But some FRBs appear to repeat, while others are apparent one-off events, suggesting that there’s more than one way to produce them (SN: 2/7/20).

      Theorists have wondered if a collision between two neutron stars could spark a singular FRB, before the wreckage from the collision produces a black hole. Such a smashup should emit gravitational waves, too (SN: 10/16/17).

      Moroianu and colleagues searched archived data from LIGO and the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, a fast radio burst detector in British Columbia, to see if any of their signals lined up. The team found one candidate pairing: GW190425 and FRB20190425A.

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      Even though the gravitational wave was picked up only by the LIGO detector in Livingston, La., the team spotted other suggestive signs that the signals were related. The FRB and the gravitational waves came from the same distance, about 370 million light-years from Earth. The gravitational waves were from the only neutron star merger LIGO spotted in that observing run, and the FRB was particularly bright. There may even have been a burst of gamma rays at the same time, according to satellite data — another aftereffect of a neutron star merger.

      “Everything points at this being a very interesting combination of signals,” Moroianu says. She says it’s like watching a crime drama on TV: “You have so much evidence that anyone watching the TV show would be like, ‘Oh, I think he did it.’ But it’s not enough to convince the court.”

      Neutron star secrets

      Despite the uncertainty, the finding has exciting implications, says astrophysicist Alessandra Corsi of Texas Tech University in Lubbock. One is the possibility that two neutron stars could merge into a single, extra-massive neutron star without immediately collapsing into a black hole. “There’s this fuzzy dividing line between what’s a neutron star and what’s a black hole,” says Corsi, who was not involved in the new work.

      In 2013, astrophysicist Bing Zhang of the University of Nevada, Las Vegas suggested that a neutron star smashup could create an extra-massive neutron star that wobbles on the edge of stability for a few hours before collapsing into a black hole. In that case, the resulting FRB would be delayed — just like in the 2019 case.

      The most massive neutron star yet observed is about 2.35 times the mass of the sun, but theorists think they could grow to be around three times the mass of the sun without collapsing (SN: 7/22/22). The neutron star that could have resulted from the collision in 2019 would have been 3.4 solar masses, Moroianu and colleagues calculate.

      “Something like this, especially if it’s confirmed with more observations, it would definitely tell us something about how neutron matter behaves,” Corsi says. “The nice thing about this is we have hopes of testing this in the future.”

      The next LIGO run is expected to start in May. Corsi is optimistic that more coincidences between gravitational waves and FRBs will show up, now that researchers know to look for them. “There should be a bright future ahead of us,” she says. More

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      The biggest planet orbiting TRAPPIST-1 doesn’t appear to have an atmosphere

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      A rocky planet that circles a small star nearly 40 light-years from Earth is hot and has little or no atmosphere, a new study suggests. The finding raises questions about the possibility of atmospheres on the other orbs in the planetary system.

      At the center of the system is the red dwarf star dubbed TRAPPIST-1; it hosts seven known planets with masses ranging from 0.3 to 1.4 times Earth’s, a few of which could hold liquid water (SN: 2/22/17; 3/19/18). The largest, TRAPPIST-1b, is the closest to its parent star and receives about four times the radiation Earth receives from the sun, says Thomas Greene, an astrobiologist at NASA’s Ames Research Center at Moffett Field, Calif.

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      Like all other planets in the system, TRAPPIST-1b is tidally locked, meaning that one side of the planet always faces the star, and one side looks away. Calculations suggest that if the stellar energy falling on TRAPPIST-1b were distributed around the planet — by an atmosphere, for example — and then reradiated equally in all directions, the planet’s surface temperature would be around 120° Celsius.

      But the dayside temperature of the planet is actually around 230° C, Greene and colleagues report online March 27 in Nature. That, in turn, suggests that there’s little or no atmosphere to carry heat from the perpetually sunlit side of the planet to the dark side, the team argues.

      To take TRAPPIST-1b’s temperature, Greene and his colleagues used the James Webb Space Telescope to observe the planet in a narrow band of infrared wavelengths five times in 2022. Because the observations were made just before and after the planet dodged behind its parent star, astronomers could see the fully lit face of the planet, Greene says.

      The team’s results are “the first ‘deep dive’ look at this planet,” says Knicole Colon, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md, who was not involved with the study. “With every observation, we expect to learn something new,” she adds.

      Astronomers have long suggested that planets around red dwarf stars might not be able to hold onto their atmospheres, largely because such stars’ frequent and high-energy flares would blast away any gaseous shroud they might have during their early years (SN: 12/20/22). Yet there are some scenarios in which such flares could heat up a planet’s surface and drive volcanism that, in turn, yields gases that could help form a new atmosphere.

      “To be totally sure that this planet has no atmosphere, we need many more measurements,” says Michaël Gillon, an astrophysicist at the University of Liège in Belgium who was not part of the new study. It’s possible that when observed at a wider variety of wavelengths and from other angles, the planet could show signs of a gaseous shroud and thus possibly hints of volcanism.

      Either way, says Laura Kriedberg, an astronomer at the Max Planck Institute for Astronomy in Heidelberg, Germany, who also did not participate in the study, the new result “definitely motivates detailed study of the cooler planets in the system, to see if the same is true of them.” More

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      A crucial building block of life exists on the asteroid Ryugu

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      Uracil, a building block of life, has been found on the asteroid Ryugu.

      Yasuhiro Oba and colleagues discovered the precursor to life in samples collected from the asteroid and returned to Earth by Japan’s Hayabusa2 spacecraft, the team reports March 21 in Nature Communications.

      “The detection of uracil in the Ryugu sample is very important to clearly demonstrate that it is really present in extraterrestrial environments,” says Oba, an astrochemist at Hokkaido University in Sapporo, Japan.

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      Uracil had been previously detected in samples from meteorites, including a rare class called CI-chondrites, which are abundant in organic compounds. But those meteorites landed on Earth, leaving open the possibility they had been contaminated by humans or Earth’s atmosphere. Because the Ryugu samples were collected in space, they are the purest bits of the solar system scientists have studied to date (SN: 6/9/22). That means the team could rule out the influence of terrestrial biology.

      Oba’s team was given only about 10 milligrams of the Ryugu sample for its analysis. As a result, the researchers were not confident they would be able to detect any building blocks, even though they’d been able to previously detect uracil and other nucleobases inmeteorites (SN: 4/26/22).

      Nucleobases are biological building blocks that form the structure of RNA, which is essential to protein creation in all living cells. One origin-of-life theory suggests RNA predated DNA and proteins and that ancient organisms relied on RNA for the chemical reactions associated with life (SN: 4/4/04).

      The Japanese spacecraft Hayabusa2 collected these samples of Ryugu on two separate touchdowns on the asteroid. The sample on the left contains 38.4 milligrams of material and the one on the right, 37.5 milligrams. Analysis of about 10 milligrams of the sample revealed the presence of uracil, a key building block of life.Y. Oba et al/Nature Communications 2023, JAXA

      The team used hot water to extract organic material from the Ryugu samples, followed by acid to further break chemical bonds and separate out uracil and other smaller molecules.

      Laura Rodriguez, a prebiotic chemist at the Lunar and Planetary Institute in Houston, Texas, who was not involved in the study, says this method leaves the possibility that the uracil was separated from a longer chain of molecules in the process. “I think it’d be interesting in future work to look at more complex molecules rather than just the nucleobases,” Rodriguez says.

      She says she’s seen in her research that the nucleobases can form bonds to create more complex structures, such as a possible precursor to the nucleic acid which may lead to RNA formation. “My question is, are those more complex structures also forming in the asteroids?”

      Oba says his team plans to analyze samples from NASA’s OSIRIS-REX mission, which grabbed a bit of asteroid Bennu in 2020 and will return it to Earth this fall (SN: 10/21/20). More